Well, the problem is not really about what you are playing compared to her or so. The problem is whether or not you are still growing under her tutelage; that's all that really matters. Regardless of whether she plays the same pieces as you or harder pieces or easier pieces than you, what matters most is that she can help you play what you need/want to play - and, help you play it
well.
I used to be very impressed with a pianist's ability to ripple through pieces or passages during a concert or during a lesson. I used to think that this autmatically meant s/he was a great pianist, a great teacher, a great musician, and that I would be lucky to just be in the same room, let alone recieve a scrap of attention or help. I don't see things in quite the same way anymore.
Yes, I am inspired by and respect an experienced artist's musical thoughts and knowledge, and yes, I do still enjoy and appreciate "good" piano playing -- and there is still a lot to be said about and learned from those things. But, I can just put a cd in the disc changer and stick my headphones on for
that anymore -- more or less.
As far as my overall quest in being able to understand pianistic playing and how to personally teach it and demonstrate it goes, I am a lot pickier now. What that means is that I would take a teacher full of teaching/musical experience and knowledge with a passion for teaching (and a passion for teaching ME) over a mere "pianist" ANYDAY (

) (there are PLENTY of the latter within the world and a lot fewer of the former) -- even if the
teacher were not playing as difficult of pieces as I play, as long as I am still making progress in a fulfilling way. If it all happens to mix together, sure, I'll take that, too. Why not ?
From what it sounds like to me, she already knows that you know what she would have to say to you. Your teacher knows that you already know where you need more work and how to fix it. So, even if it is time to move on, my question to you is if you are really doing your job as a student anymore ? If you know what needs work and if you know how to fix it (provided that is indeed true), why are these problems still there ? If you do not know how to fix these problems or if you do not know what these problems actually are, why are you not specifically asking your teacher for help in these spots ?